Method of disinfecting floors by injecting hot, wet compressed air into the floor, this air being produced by a generator, whether on board or not, consisting of two cylinders of different diameters, one (1) of large diameter into which the atmospheric air is drawn and then compressed in a chamber (11) to a pressure and temperature sufficient to allow almost instantaneous vaporization of a dose of liquid and the other (6), facing the chamber, of smaller diameter in which the charge of humidified compressed air will be partly expanded so as to bring it back to the chosen pressure and temperature for use in order to inject it into the floor.